Comments, yeah I got some.
One thing I have decided after 14000 miles is the Spyder is NOT a motorcycle. Doesn't lean, no counter steer etc. Comparisons of a Spyder to a motor cycle are like apples and oranges.
If you want to compare it to something with similar handling characteristics, you need to look at snowmobiles. Remember, the first prototype was an SkiDoo MXZ snowmobile with ski's and track replaced by wheels. That is where the Spyder's heritage lies. And when you do that, you can cross reference fairly reliably as to what a change like bar risers will get you.
Years ago on snowmobiles I discovered that bar risers gave me MUCH more control over my weight distribution and consiquently better overall handling of the machine, especially in tricky or adverse conditions and aggressive riding situations. This is what I found true when I put the risers ( I have the BRP 1", installed before delivery, and the No Magic Neon 3" installed the first day available) on my Spyder also. With the weight off my hands The Spyder is MUCH easier to steer. Just like it is more twichy if your grip is not relaxed on the handlebars, if you put weight on the bars through your arms and shoulders, you feel less in control. Try steering with one hand for a while on a stock Spyder and you will quickly find it is not very comfotable. Put the bar risers on and it becomes much better and more comfotable to do this.
Because it's NOT a motorcycle, the Spyders stock riding position is not optimal for most of us. The weight you carry on the handlebars prevents you from being able to easily shift your weight from side to side in the saddle. With the risers you are able to keep your weight centered more in the saddle and therefor able to more easily transfer weight from side to side, because you are not restrained by supporting your upper body on the handlebars. When you get your weight hung out to the side (again, think snowmobile) you can really effect a change in the vehicle CG and the easier that is, to more likly you are to do it. A benefit of this is that the more you move the CG to the side the longer the nanny remains asleep and the faster you can negotiate the corners.
So my conclusion is that the bar risers are the best immediate performance gaining mod for the money available, as well as a comfort mod that makes longer rides possible and more enjoyable.
Hope this helps.